P1:Energy

P1:Energy

1. Energy stores

   • thermal
   • kinetic
     • K.E.(J)= 1/2 mv^2
   • Gravitational potential
     • GPE(J) = mgh
   • Elastic potential
     • E.P.E= 1/2 ke^2
   • chemical
   • magnetic
   • electrostatic
   • nuclear

2. Specific heat capacity

   • the amount of energy it takes to heat a kg of a substance by a degree
   • Change in thermal energy = m X c X temp change

3. Power

   • P= Energy transferred/T(s)
   • P=Work done/T(s)
   • Rate of energy transfer/work done (W)

4. Conduction and convection

   • conduction
     • mainly in solids
     • When vibrating particles transfer energy to neighbouring particles
     • Though collision
   • convection
     • only in particles and gases
     • When energetic particles move from hotter to cooler regions
     • heat reduces density, meaning hot particles rise
     • creates convection current
     • radiators

5. Unwanted energy transfers

   • lubrication reduces frictional forces
   • insulation reduces energy transfer through heating
     • less energy lost to outside

6. Efficiency

   • =useful output energy transfer/ total input energy transfer
   • useful power output/ total power input

7. renewable energy

   • never runs out
   • damage the environment, but not as bad as non renewable
   • don't provide as much energy
   • some are unreliable- based on weather

8. non renewable energy

   • Will run out one day
   • damage the environment
   • provide most of our energy
   • more reliable
   • natural gas and coal
   • fossil fuels